To test their model, the team took tissue samples from a mouse whose brain had been bioengineered to make larger neurons in the cerebral cortex express a fluorescent protein (found in jellyfish), making them glow yellow-green. Because of this glow, the researchers were able to see synapses against the background of neurons.

Wait. They genetically engineered a mouse with fluorescent neurons? Then they magnified it — how? — so that they could see these very, very tiny fluorescent neurons? And they built a detailed, navigable computer model of it?

They found that the brain’s complexity is beyond anything they’d imagined, almost to the point of being beyond belief, says Stephen Smith, a professor of molecular and cellular physiology and senior author of the paper describing the study:

Of course. How else could it be the kind of thing that would combine just the right genetic material from jellyfish and mice to create fluorescent neurons that they could make an interactive map of, record, and post so that whoever wants anywhere in the world can see it at any time? How else would it belong to the kind of being that would even want to?